Automatic telephone system



Oct. 27, 1925. 1,559,371

W. T. POWELL AUTOMATIC TELEPHONE SYSTEM Filed June ll. 1920 I5 Sheets-Sheet 1 i I i l l l TERMINA'HHG PRIMARY ALLOTTER.

PRHVRY FINDER.

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INVENTOR WINFRED T. POWELL.

Non mDvCTNE ATroRNEY 3 Sheets-Sheet 2 W. T. POWELL Filed June 11, 1920 AUTOMATIC TELEPHONE SYSTEM M@ A QR EMU] moi Oct. 27, 1925.

W. T. POWELL AUTOMATIC TELEPHONE SYSTEM Filed June 1l, 1920 3 Sheets-Sheet :5

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ATTORNEY wm h Patented Oct. 27, 1925.

UNITED STATES PATENT OFFICE.

WINFRED T. POWELL, OF ROCHESTER, NEW YORK, ASSIGNOR TO THE STROMBERG- CARLSON TELEPHONE MANUFACTURING COMPANY, 0F ROCHESTER, NEW YORK,

A CORPORATION OF NEW YORK.

AUTOMATIC TELEPHONE SYSTEM.

Application filed .Tune 11, 1920.

Be it known that l, VINFRED T. POWELL, a citizen of the Fnited States, residing` at Rochester, in the county of Monroe and State of New York, have invented certain new and useful iniprovements in Automatic Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systems, and more particularly to telephone systems employing automatic switches in extending a telephone connection from the calling to a called suhscriliers` line.

The main feature of this invention consists in the provision of means for electrically distinguishing a wanted subscrihefs line, and thereafter starting primary and secondary automatic switches to locate the line so distinguished.

Other features of the invention will appear from the detailed description and claims.

The drawings with Figs. 1, Q and 3 arranged in the order named` diagrammatieally represent a portion of the telephone system employing they present invention.

At the left of the dotted line of Fig. 1, there are represented the substations and line circuits of two subscribers lines. For purposes` of this descrilition the line designated A, is referred to as the calling line and the line designated l5. is referred to as the called line` although it will be understood that each line may function as a call ing or called line. lithin the dotted rectangles at the center portion of Fig. l, there is represented two switches which are refcrred to as primary linder switches. These switches may he switches of the same or different groups depending on whether the calling and called linesl are in the same or different groups. lithin the rectangle at the hottom ot' Fig. l, and within the reeu tangle at the top of this tigure there are represented two switches, Ythe first designated originating primary allotter, and the second terminating prin'iary allotte-r. There is one of these pairs of switches for each group of primary finder switches. At the right ot Fig. 1, and at the left of Fig. 2, there are shown two secondary nder switches: one of these switches co-operating in extending a call from a calling line which Serial No. 388,207'.

switch is referred to as an originating secondary tinder, and the other which functions to extend a call to the called line, and this switch is referred to as a terminating secondary finder. At the lower lett hand corner of Fig. 2 there is diagrammatically shown a switch which is called an originating secondary allotter. This switch functions to assign an idle originating secondary tinder switch for each calling line. At the right of Fig. 2 and at the left of the dotted line of Fig. i3, there are shown a tens register and a units register. These two registers cooperate and are referred to a register sender. At the upper right hand corner of Fig. there is shown a group otl ten relays provided with a plurality of contacts. 'lhese relays are common to all the lines` ol' the system. and each line is represented by a contact in some one of these relays.

The present invention has been represented in a s vstem having 10() lines. In such a system the lilies are arbitrarily divided into four groups, each having 25 lines. For the individual use otl each group of Q5 lines there are provided 8 primary finder switches which may function to connect to a line irrespective of whether it is calling or being called. Fach group of lines also has for its individual use an originating primary allotter for assigning any one of the t5 primary switchesv Vfor use when idle inthe case oll :in originatingl call. and the terminating allotter functions to assign any idle one of the saine 8 switches to locate the called line in the case of a terminating call. Twenty secondary finder switches, each provided with 32 of terminals and having access to the 8 primary switches of each of the L groups are employed. Ten of these secondary finder switches are used onlytor extending a call from a calling line, and the remaining it) secondary switches are only used to extend a call to the called line. A single allotter switch herein referred to as the originating secondary allotter functions to assign the 10 originating secondary tinder switches for use in succession when they are idle.

The switches employed in this system may he of a structure substantially similar to that disclosed in the patent to Clement, No. 1,107,153, issued Augustl l1, 19141 and may all be oi' the hsaine design yexcept that the number of sets of terminals 'in` the switch and the brushes co-opcrating with the same may vary in number. For example, the primary tinder switches are provided with 25 sets ot terminals and with 5 brushes for cooperating with the sets of terminals. The primary aliotters are provided with 8 sets ot terminals and with 4 sets of brushes :tor engaging these tern'iinals. The secondary finder switches are provided with 32 sets ot' terminals and )viti 4 sets ot brushes for co-operating therewith. 'Ille originating secondary allotter has l() sets of terminals and 3 sets ot brushes, while the tens and units registers have l1 sets of terminals pro-- vided with 2 sets of brushes and 3 sets rcspectively.

Briefly the operation of the system is as follows: Vhen the calling subscriber removes his receiver from its switchhook, an allotted primary finder switch in the group associated with the calling line is started to lind the calling line. Simultaneously a secondary finder switch is started to locate a primary finder switch that has begun to operate. The first of .these switches to complete its operation will wait for the other to complete its function, and the calling line will then be extended to an idle register sender. The subscriber now operates his dial switch to set the tens register in accordance with the tens digit of the wanted number. Thereafter the dial switch is again operated to set the units register in accordance with the units digit of the wanted number. After the number is thus registered, the called line is tested and, it idle, is characterized by a condition which will cause a primary finder switch of the group in which it is located to seize the line terminals. Also a terminating secondary finder switch associated with vthe originating sccondary tinder that has been taken for use operates simultaneously with the primary Iinder switch that is locating the called line. Then these last mentioned primary and secondary finder switches have located the called line, thc called line is signaled and the talking and releasing functions then take place. It will be noted that the register sender taken for use in extending a. call, is retained until this call is terminated, or abandoned.

lt is believed that the invention will best be understood by describing the operation ot' establishing a telephone connection from a calling substation, ysuoli as A to a called substation, such as B. It will tirst. be assumed that the called substation is idle, and it will thereafter be assumed that the called substation is busy.

When the subscriber at A removes his receiver from its switchhook, a circuit is closed Ier the line relay 5, from grounded battery.

its Winding, through thetlower back contact and armature of the cut-off relay 6, through the substation circuits of the substation at A, inner upper armature and back Contact of the cut-oit relay 6 to ground. The line relay 5 attracts its armatures and .closes a circuit from ground, at the lower back contact and armature ot relay 7, inner contact and armature of relay 5, winding ot relay 8, back contact, armature and winding of the motor magnet 9 of the originating primary allotter to grounded battery, unless this allotter is engaged in assigning an idle primary finder switch for use, under which condition the relay 8 will be short circuited by a circuit completed from grounded battery, winding, armature and contact ot the motor magnet 9, allotter-brush 10, to ground at lower front contact and armature of relay 11 or at the outer right hand front contact and armature of relay 23. As soon as the originating primary allotter is standing with its brushes associated with the allotted idle primary iinder switch, the circuit described Jfor the .relay 8 will be effective to energize this relay and it will close a circuit tor advancing the primary finder switch into engagement with the terminals of the calling line. This circuit extends from grounded battery, resistance, upper-most armature and front contact of relay 8, allotter brush 12, winding of the motor magnet 18, armature and back contact of this motor magnet, allotter brush 14 to ground. Vhen the relay 8 operates, it also closes a circuit yfrom ground, its inner-most armature and front contact, allotter brush 15, winding ot relay 16 to grounded battery.

The relay 16 when energized closes two circuits, one of which places a busy potential on the test terminal 17 of the primary finder at the terminating primary allotter switch, and at its right hand armature and front contact closes a break point Vin the stopping circuit for the originating secondary finder switch as will be described. Also when relay Skoperatcd, it closed at itsl lower armature and front contact a circuit fiom ground, through the winding of relay 1,8, back Contact, armature and windingof the motor magnet 19 oi the originating secondary allotter to grounded battery. The magnet 19 does not operate in series with the relay 18, but the, relay 18 is energized and closes an operating circuit for the originating secondary finder switch troni grounded battery, resistance, armature and front contact ot relay 18, originating secondary allotter brush, winding ot the motor magnet 20, its armature, back contact and allotter brush 21 to ground. It will thus be seen that relay 8 simultaneousl Y starts an allotted primary and an allottedy secondary {inde-r switch to extend a connection from the callingline to the register sender.

When the line relay 5 operated, it closed a circuit from ground at the lower armature and back contact of relay 7, through its armatures and contacts in series, to all the multiple terminals suoli as 21 at all of the primary finder switches in the group in which the calling line is located. As soon as the started primary tinder switch engages the set of terminals individual to the calling line, the ground potential on test terminal 2l is extended over the tinder brush 22 armature and back contact ot relay 23, winding of relay 24, allotter brush 12, uppermost front contact and armature of relay 8, and resistance`to grounded battery. lt Will be noted that this last traced circuit shunts the motor magnet l?) of the primary finder switch, causing this switch to stop with its brushes in engagement with the terminals of the calling line. The relay 24 is energized in the circuit just described and attracts its armature to extend the holding circuit of the primary tinder switch to the secondary tinder switch.

It. will be remembered that the circuit for the. originating secondary linder switch was Completed through the brushes llt) and 2l ot the originating` secondary allotter. Under the control of this circuit, the allotted originating secondary linder switch advances its brushes until its test brush 25 eugages the terminal 26 associated with the primary finder switch that has been engaged in locating the calling line.

As soon as the test terminal 26 is tested, the stopping circuit previously mentioned for the originating secondary tinder switch is closed from ground, outer armature and front'l Contact ot relay lt, test terminal 26, test brush 25 of the originating secondary finder switch, winding ot' relay 27, allotter brush llt), front contact and armature ot' relay 18, and resistance to grounded battery. This circuit is eti'ectiye to energize the relay 27 and also to shunt the motor magnet 2t) to stop the originating secondary linder switch in engagement with the terminals of the primary linder switch engaged in locating the calling line. 'hen the primary and secondary tindex' switches have been oper ated and stopped in the manner just de.- scribed, the relays 2t and 2T will be operated and a circuit will bey closed from ground. winding of the cut-ott relay (i, terminal 28, tinder brush 2t), upper ari'nature and Yfront contact ot rclay 24, winding ot relay ll, secondary tinder terminal 30, secondary finder brush 31, conductor 32, front contact and armature ot' relay 2T, winding ot relay 27, winding of relay 3? to grounded battery. A circuit in multiple with that iust described is closed through relay 56. The relay 5G at its upper armature and contact closes a circuit tor energizing relay 5i' (Fig. to close other circuits as will be described, while the cut-ofi' relay (i in operating disconnects the line relay 5 from the calling line, and at its upper-most armature and back contact opens the test coiuluctor 34, which prevents the calling line. trom being seized as a called line. The relay l1 closes a locking circuit t'or itself and thus maintains the holding circuit independent ot the arinature and contact of the relay 24. The relay 311 on attracting its armatures closes a break point; in the talking conductors of the link circuit associated with the secondary finder switch, and also eliminates the control of the relay 27 over the holding circuit by extending this circuit through an armature and front contact of the relay 33. lVhen the relay lo closed the break points in the talking conductors extending through the link circuits to the calling subscribers line, stepping relay 34 was energized. This circuit may be traced trom grounded battery, lower winding ot the stepping relay 31.-, over the connection linst built up, through the upper winding` ot the relay 34, conductor 37, brush 38 ot the units register in its normal position, winding of the induction coil 39 to ground. The stepping relay SR, is energized in this circuit and operates the lslow releasing relay 35, which in turn operates the 'slow rel-casing ielay 90. The apparatus and circuits are now in condition to receive the impulses corresponding to the tens digit ot the wanted number. This condition will be indicated to the alling subscriber by the application of a dialing tone through windings of the induction coil. All the subscribers may be instructed not to operate their dial switches until this tone is heard.

Let it be assumed that the number ot the wanted station is S9. rllhe calling subscriber will therefore operate his dial switch to transn'iit S impulses in response to which the armature of the stepping relay 3l is vibrated. "hen the armature ot' the stepping relay 34 is retracted in response to the lirst impulse of the tens series, the slow releasing relay 3G is actuated in a circuit extending from grounded battery, winding ot this relay, upper t'ront contact and armature o'l' relay 35, back contact and armature ot relay 34 to ground. telay 35 as is well known controls the restoration ol' the tens and units registers as will be described. Also in response to the tens series ot impulses the motor magnet 4t) ot the tens register is operated once for each impulse transmitted. The circuit for controlling the motor magnet extends from grounded battery, winding of the motor magnet, upper back contact and armature of relay 4l, upper front contact and armature ot' relay 35, back contact and armature of stepping relay 34 to grouiid. Under the control of this circuit the brushes 42 and 44 ot the tens register lll() lltl are advanced until brush 44 engages contact 45, which contact is allotted to all the lines of which the tens designation is the numeral 8. At the close of this tens series of impulses, the stepping relay n4 will hold its armature attracted for a relatiijely long interval, permitting the slow releasing relay 3G to retract its armatures. In respons-c to `this retraction, a circuit is closed from ground, upper armature and back Contact of relay 3G, continuit-y Contact and spring ot switching relay 41, units register brush 42, back contact, armature and winding of the motor magnet 40 to grounded battery. rfhe motor magnet 4() does not energize in the circuit last described, but the relay 41 attracts its armatures and is lock-cd operated through its lower armature to ground, so that the stepping relay 34 now repeats its impulses to the motor magnet ot the .lullts register instead ot to the motor magnet of the tens register as last described.

The calling subscriber now operates his dial switch to send 9 impulses corresponding to the units digit ot' the Wanted number. In response to this series of impulses, the stepping relay 34 again yibrates its armature, but now closes a circuit trom ground. its armature and back Contact, upper armature and front contact ot' relay 35, upper armature and front contact of switching relay 41, conductor 46, inner upper armature and back contact of switching relay 47, conductor 48, winding of the motor magnet 49 of the units register rto grounded battery. In response to each impulse repeated by the stepping relay 34, the motor magnet 49 is operated, and Since it `has been assumed that 9 impulses are transmitted the units register will advance its brushes 38, 50. and 5l until its brush 51 is in engagement with the contact. 52. At thev close okt the units series ot' impulses the switching relay 47 is operated in a circuit extending from grounded battery, winding, arma-ture and back contact of the motor magnet 49, the units register brush 5t). conductor 5,3, winding of switching relay 47, cmiductor 54, upper back contact and armature of slow releasing relay 3G to ground. The relay 47 is energized in this circuit and attracts its armatures to close a locking circuit for itselic from ground, its lower armature and front contract to grounded battery at the motor magnet 49.

It will be remembered that lthe slow releasing relay 5T was energized as soon as relay 56 was operated. Vith the relays 57 and 47 actuated, a circuit is closed for operating relay 58 from grounded battery, -winding of this relay, lower front contact and armature of relay 57, upper-most armature and continuity spring of relay 47, conductor 59, back contacts and armatures oi. com iuon lock-out relay 60 to ground. Relay 58 at its inner-most armature and back contact interrupts ,the locking circuit of the ,relay 57, but since this relay A57 Ais slow releasing it will hold its armatures attracted for an appreciable interval after its, o erating circuit is broken, and relay 58'wigll e held operated for a short interval. t the middle armature and `front contact 'relay 58, a circuit is extended from ground', `through registcrlrrush 4 4 and Contact 45, conductor (il. winding ot relay G2 to groundedbattery. The relay v62 is` operated in this circuit to close its contacts. At `the up` ,er-most armature and trout Contact of re ay 58 a circuit is extended from ground over conductor 63, upper winding of yrelay 64, conductor 65, units re rister brush 51, Contact 5,2, contact .G6 of relay 62 which contact is indiyidual to the subscriber Whose number is 89, test conductor 6,7, upper-most armature and back contact of the'cut-Qjtl relayS of the .socalled line, lower andl upper winding in scr-ies of rela j to grounded battery.u "The relays 64 an 7() are o erated in series, and the relay 70 locks itStff operated in a circuit extending from rounded battery, through both of its windings in series. upper-most back contact and armature ot' the cnt-oft relay 68, lower front contact and armature of relay 70 to ground. Relay v64 also locls itself operated in a circuit extending from grounded battery, through both of its windings in series, upper-most back contact and arma-ture of the cut-ott` relay (i8. lower front Contact and armature of relay 70 to ground. Relay 6 4 also locks itself operated in a circuit 4corrrlpleted from grounded battery, winding of the connnon lock-out relay 60, conductor 71, lower winding, front contact and arm lture of relay 6 4, conductor 72, uppelfmostl ack Contact and armature of relay 73 to ground. The energization of the relays 70 and 6,4 serve to start the primary finder switch and the termiliating Secondary liuder switch to complete the extension of ,the link circuit to the called line while the collimon lock-out relay Gt) permits only one called line to be tested at a time. Itis assulned that the terminating primary allotter is Standing with its brushes in engagement. with an idle primary finder switch ot the group in which the called line is located. Under these conditions as soon as the relay 70 is operated, it closes a circuit from ground, its inner upper armature and front Contact, winding of relay 75, back Contact. armature and winding of the motor magnet 76 of the terminating primary allotter to grounded battery to operate relay 75. With the relay 7 aopeiated. a circuit is closed for operating the relay 76 from grounded battery, winding of this relay, allotter brush 79', u ,per-most front Contact and armature of relay to ground. The relay 7G is thus caused to attract its armatures and now rendersr test brush 77 effective instead ot the test brush 78 which is effective when the primary tinder switch is hunt-- ing for a calling line. Relay also closes an actuating circuit t'or tht` motor nmgnet 79 of the allotted primary finder switch, which circuit is completed from grounded battery, resistance, inner-most armature and front contact ot relay 75, allotter brush 80, winding of the motor magnet 79, its armature and back contact, allotter brush 81 to ground. Under the control of this circuit the primary finder switch advances its brushes until the tinder test brush 77 engages the test terminal 82, which is individual to the called line, at which time a circuit is closed from ground, upper-most armature and front contact ot' relay 70, test terminal 82, test brush 77, left hand front contact and. armature ot relay 76, winding of relay 83, allotter brush 80, inner-most front Contact and armature ot' relay 75. resistanceto grounded battery. This circuit serves to operate the relay 83 and to shunt the motor magnet 79 of the primary linder switch which is now in engagement with the terminals 'bf the called line. Vhile the primary finder switch is hunting for the called line, the terminating secondary finder switch hunts for the trunk circuit individual to this last mentioned primary finder switch. The operating circuit for the secondary finder switch is completed as soon as the relay 64 is operated, and is traceable from grounded battery, resistance, upper armature and front contact of relay 64, winding. armature and back contact of the motor magnet 84 of the secondary tinder switch, lower front contact and armature ot relay 64, conductor 72, upper-most back contact and armature of relay 73 to ground. The trunk circuit individual to the primary finder switch that is hunting for the called line is electrically distinguished by the presence of ground potential on its test terminal 85. This ground potential is applied at the innermost front contact and armature ot relay 76, and as soon as the terminating secondary indcr switch advances its test brush 86 into engagement with the test terminal 85. a circuit is completed over conductor 87, winding ot' relay 88, conductor 89. upper front contact and armature ot' relay 64, and resistance to grounded batterv. This circuit is effective. to operate relay 88 and lo shunt the motor magnet 84 of the terminatingr secondary finder switch, thus causing it to stop with its brushes in engagement with the terminals of the link circuit individual to the operating primary finder switch. As soon as the primary and secondary linder switches have completed the extension of the connection to the called line, a circuit is completed from ground, winding of the cut-0Hl relay 68 of the called line, primary finder brush 91, armature and front contact of relay 83,

winding of relay 92, secondary finder switch brush 93, conductor 94, armature and contact ot relay 90, armature and t'ront contact of relay 88, winding of relay 73 to grounded battery. The relays 73, 92 and cut-oit relay 68 are operated in this circuit. The relay 92 at its upper armature and front contact closes a substitute circuit about the armature and front contact ot relay 83 and the relay 73 at its inner-upper armature and front contact eliminates the arlnature and front contact of relay 88, from the circuit just described.

As soon as the relay 73 operates, a circuit is closed for actuating the ringing relay 95 extending from grounded battery, resistance, conductor 96, winding of relay 95, conductor 97, inner-most lower front contact and armature ot' relay 73, conductor 98, and back contact and armature of relay 99 to ground. Relay 95 on attracting its armatures causes ringing current to be transmitted from the well known type of ringing machine, over conductor 100, right hand winding of relay 101, lower front Contact and armature of ringing relay 95, over talking conductor 102 and the link circuit to the called substation and bell, over the other side of the line and link circuit to talking circuit to conductor 103` resistance. upper front contact and armature of ringing relay 95, upper-most front contact and armature of relay 73 to ground. Ringing current is applied over this circuit until the called subscriber responds by removing his receiver from its Switchhook whereupon the trip relay attracts its armature in the well known manner; and the ringing relay 95 is short circuited at thc right hand armature and front contact of the trip relay 101, causing the ringing relay to de-energize, disconnect the ringing current from the called line, and connect relay 99 to the called line. Battery feeding relay 99 has its windings serially included in the talking conductors 102 and 103. Relay 99 is operated in this circuit and closes a substitute circuit for the slow releasing relay 90, which controls the release of the register sender as well as releases the primary finder switch and the terminating secondary finder switch. This substitute circuit extends from grounded battery` resistance, winding ot the relay 90, front contact and armature of relay 90, front contact and armature ot relay 99 to ground. Talking battery is supplied to the calling subscriber through the windings ot stepping relay 34. while talking battery is supplied to the called party through the windings of relay 99.

lVhen the called subscriber replaces his receiver on its switchhook, the stepping relay 34 de-energizes and shortly afterward the slow releasing relay 35 de-energizes to close a circuit for the motor magnet 40 of the tens register. This circuit extends from Cil grounded battery, winding, armature and backy contact of the motor magnet 40,. tens register brush 42, back Contact and armature ot' xrelay 33, back `contact and armature of relay 34 to ground. Under the control of this circuit, the motormagnet l0 `advances the Abrushes of the 'tens register until the brush is restored to its normal position at 'which timefa circuit yis closed ft'rona ground, armatures and "back conitacts'oi relays 34 and 35. dens register brush 42, ainits register brush 50. back contact, armature and ywinding of the motor magnet 492, to @rounded battery. Under the'control ol this tlast nicntionied circuit, the motormagnet 49 adlvanccs the brushes of 'the unitsregister until they are restored to their :normal position. With the register brush 5() in its normal position, the `look'ufng circuit ott the switching relay 47 Iis intemupd causing this relay to retract its armatures.

Atthertime when'the stepping relay 34 deenergined anzdgfbe'fone 'the slow releasing relay 35 retracted its armatures, n circuit was vmornentanily lcompleted for the slow releasing relay 36. Subsequently the lslow releasing relay 35 retracted its ar1natiires,bnt before relay 36 'rct'racts its-armabiires a oircuit was closed Einem ground, lower `armature and. .back contact of relay 35, lower armature and front contact of relay 36, windingffof relay T33 to grounded battery :und in multiple vwith the Winding of relay 56 `to grounded battery. This last traced circuit is eifi'ective Vto' short circuit `the cutoff relay 6 of :the calzli-nrgr` line lfand the relay 11 on' the' primary finder switch. Finally whenrelay 36 die-energnes, itherelays 33 and 56 Kcleeinengize. The calling line is new in normal condition and Athe primary linder switch ,as well as the originating secondary linder switch remain with'their brushes in engagement' wlith #the `-terlfninnls 'last 'i-ised.

Vh-'en the-called subscribe/n replaces his re ceifver onl its switohliook, til-ie relay l99 re# tracts its armature and closes a ci-rcfuit fronrground,armature and front contact oft' the Ktrip relay 101, cofndi'ictor 96, and vresistance togrr-ui-nded vbattiery. This places -a short circuit about the slow releasingA vrelay 90, which causes -i't -toretraot iitsarmaturcs and thereby opens Ythe holding circuit including the relays 73, 92 and the cut-oil' rclay 68. These last mentioned-relays de-energize leaving 'the called linie in normal cond-ition and leaving theprimary finder switch and the terminating .secondary finden switch in engagement with the'iterininals last used.

if the called line is basy when the relay o8 of 3 operates., thefrelay: 64 will not be operated becausey the test circuit 67 of the called line will belopen at the upper-most armature andy backV oontacti of the cut-olf relay 66. Since-the' relayfl is not operated, the terminating secondary finder switch will not be advanced, and since the relay 70 Yassociated with 'the called line is not energized, the terminating primary allotter and the primary finder switch will not be operated. Under this condition a busy tone will be transmitted to the calling subscriber overa circuit extending from the busy machine BZ, inner lower armature and front'contact of the relay 56, conductor 106, upper-most armature and back contact oil slow releasing relay 57, .loweiwmost armatu-rc and back contact ol relay 7 3, conductor 107, armature and back contact of relay 6l, through the condenser, uppermost front Contact and armature of relay 33, through -the originating secondary iinder switclr and the -primary Vfinder switch of ythe calling line and over the other 'Side `of the connection to 'the middle armature of relay 33, through the condenser, righ-t hand winding of relay 99 to ground. The calling subscniber on 'receiving this busy signal releases the connection by replacing his receia'er to its switchhook, whereupon the reg-is- .ter sender'and the primary finder switch vas well as ythe originating. secondary finder switch wiil-l take 'place in the manner previously -descnibedt lit wil-l be noted that the originating primary allotter will move to a position to am sign another :primary vinder for use as soon as either of f'thefrelays 11 and `23 ot' the pirimary linders are energized, since an operating circuit is closed `for the `allotter from grounded battery, winding, varmature and back contact o-f motor magnet 9, allotter brush l() vto ground at the armature of either relay 11 ofr 2?. Similarly the operatioi-i otl either relays 92 'or 11'() 'control t'lie setting oft the terminating primary allotter, while relay 56 controls the adjustment of the originating secondary allotten Wdh-atl claim is:

1. ln a telephone system, -a plurality of telephone lines, a plural-ity lof nonmumericul switches of the step by step type, `a plurality of itrn'iilis, means Vfor causing a non-numerical switch 4to seize a calllii-ig line. means to ca use a second non-numericalswitch having wipers to successively test Said lines and to seize a wanted line. and means including a trunk circuit said nim-numerical switches only for i-nterllinliing. said last n1cn tioned switches.

2. In a telephone system, 'a plurality of telephone lines, a plural-ity ot' -non--minierical switches, a plurality ot' trunks', a register sender common to aplurality of said trunks, means for selectively adjusting said register sender in accordance with the desi nation of a wanted line, means for-distinguis ing a wanted line as indicated by the adjustment of said register Sender, means-for causing a nonfnnlnerical switch having. wipers vto hunt for and seize the called line so distinguished, and a telephone connection inl cluding non-numerical switches only and at least one ot' said trunks.

3. In a telephone system, a plurality of telephone lines, a plurality of non-numerical switches, allotting devices Jfor assigning said switches tor use, a plurality ot' trunks, means for causing an allotted non-nmnerical switch to seize a calling line, means for thereafter "ausing a second allotted non-numerical switch to seize a wanted line, and means including only trunk circuits and non-nu merical switches Vtor interlinking said last mentioned switches.

4. In a telephone system, a plurality ot telephone lines, a plurality ot progressively movable non-numerical switches, a plurality ot' trunks, a register sender con'nnon to certain of said trunks, means tor selectively adjusting said register sender in accordance with the designation ot a wanted line, means for distinguishing a wanted line as indicated by the adjustment of said sender, means for causing a non-numerical switch to hunt for thel called line so distinguished, and a telephone connection including only said non-numerical switches and a plurality ot said trunks.

5. In a telephone system, a plurality of telephone lines, a plurality ot non-numerical switches having Wipers capable ot assuming a plurality of selective positions, means tor causing one non-numericalswitch to seize a lalling line, means Ytor causing a` second non-mnnerical switch to seize a wanted line, and means including trunk circuits and non-numerical switches only l'or intel-linking' said last mentioned switches.

(t. ln a telephone system, a plurality ot telephone lines` a plurality ot` non-numerical switches operating simultaneously to extend a calling line to a trunk circuit, and a plurality ot' other progressively movable automatic switches operating simultaneously to extend said trunk to a wanted line.

T. The method oll extending telephone calls. which consists in simultaneously building up two portions ol. a connection trom a calling line. registering the desig` nation ot. the wanted line at a remote point over said partially extended connection, causing this registration to characterize said line by a selectable condition, and then simultaneously building up two other porv tions ot' the connection from said tirst mentioned portions ot the connection to the line so characterized.

tl. ln a telephone system. a group ot' telephone lines, a group ot' min-numerical switches t'or connecting with said lines whether calling or called, two sets ot allotters for assigning switches for use dependent upon the operation in which said switches are employed, means for causing one of said allotted switches to seize a call ing line on the initiation of a call, a second group ot switches t'or connecting with an allotted switch ot' the tirst group ot' switches on the, initiation ot a call, an additional allotter for assigning switches ot' the scond group for use, means controlled from a distant point to receive the designation of the wanted line and thereafter distinguishing a wanted line by a selectable condition, a third group ot non-numerical switches, one et' the second group ot' switches being linked to a switch ot the third group, means under the control ot the said sender to cause one ot said tirst group of switches to seize the distinguished line, and means including one of said third group ot switches tor eX- tending the calling line through a switch of each ot said lirst and second groups of switches to the switch that has seized the called line.

t). In a telephone system, a plurality of telephone lines,r a plurality ot test circuits therefor, a plurality of non-numerical switches. a sender comprising tens and units registers, a group of relays common to all ot said lines, each ot' said relays being common to a different group of said lines, said relays controlling break points in the testingl circuits ot said lines, means controlled t'rom a distant point to adjust said tens register in accordance with the tens designation of the wanted line and thereby actuate one ot said relays` means controlled trom a distant point for actuating said units register to close a second break point in the test circuit ot the wanted line, whereby said test circuit is completed to electrically distinguish said wanted line, means tor causing a nonnunierical switch to seize the line so distinguished, and a telephone connection extending through said actuated non-numerical switch.

lt). ln a telephone system, a plurality ot' telephone lines. a group ot' nonmnnerical switches for connecting with said lilies whether calling or boing called, an allotter `for assigning a switch Vfor use when one ot' said lilies is calling. a second allotter t'or assigning an idle one ot said switches For use when one ol said linesl is being called. a register sender and a graag;- ol relays ar ranged to he selectahly adjusted trom a distant point to distinguish the wanted line, test circuits under the control ot a register sender and said I`group of relays to characterize the wanted line by a selectable condi` tion` means tor starting an allotted non numerical switch to hunt tor the line so characterized, and a telephone connection between said calling and called lines including two non-numerical switches.

11. In a telephone syst-em, a plurality ot telephone lines, a plurality of primary trunks, means for allotting idle trunks for llt) use` a primary non-numerical switch individual to each trunk, means for operating the primary non-numerical switch of the allotted trunk to connect said trunk to a calling' lin@I on the initiation of a call, seeondary trunks3 soeondary non-numerical switch for each end of each secondary trunk, means for allottingr idle secondary trunks Ylor use, nie-uis ifor operating a secondary non-nmlrerical switch of the allotted seoondar'y trunk to Connect said trunk to 'the primary trunk now connecte-d to the calling line` a legrisl'er sender arranged to be variahly adiusted over said calling telephone line and primary trunk in series to desig nate any other telephone lin-e as a wanted line, a plurality of starting eireuits, a group of multi-contact relays common to said telephone lines, said multi-contact relays and said register sender cooperating' to close the starting eireuit of the wanted telephone line, and means including a primary nonnumerieal switch and the other secondary non-numericai switch ol the allotted seeondary trunk for connecting' the wanted telephone iine to the selected secondary trunk.

In witness whereof, I hereunto subscribe my name this 8th day of June, A. D. 1920. VINFRED T. POVVLL. 

